In our previous work, we have identified a definite association between decreased ability to metabolize galactose and pre-senile "idiopathic" cataract formation. We have also studied cataract formation in diabetics and demonstrated a positive association in this prospective, controlled study. Various diabetic variables, including the age of the patient, diabetes duration and treatment, fasting blood sugar, race of the patient, and the influence of concomitant glucose-6-phosphate dehydrogenase deficiency, have been analyzed, and their impact on the formation of diabetic cataracts quantitatively evaluated. In the proposed study, the patients with an impairment of galactose metabolism and the presence of early, asymptomatic cataracts will be placed on a low galactose diet, and the effect of the diet will be evaluated by periodic clinical and stereophotographic evaluation of their lenses. The patients' compliance will be monitored by analysis of galactose derived alcohol-dulcitol in their red cells by chromatographic means. Likewise, the impact of diabetic control on the development of diabetic cataracts will be studied in a prospective manner.